The present invention relates to a method of covering steel parts on the outer surface of which there is applied a plastic coating which is or can be brought in contact, at least in individual regions, with an embedding material, the interface formed by the outer surface of the plastic coating with the embedding material being provided with profiling projections.
One such method is known from Federal Republic of Germany OS 35 31 618. In that case a steel pipe is provided with a layer of thermoplastic resin over which an outer coating having a base of concrete is then applied. The plastic coating is produced by helical overlapping wrapping with an extruded foil tape which is provided with at least one thickening which extends in strip shape over the entire length of the foil tape. The thickening is arranged on that edge of the foil tape which is not overlapped by a following layer of the foil tape.
The concrete coating serves, in particular, to increase the weight of the pipes so as to counteract by additional weight, the hydrostatic buoyancy of empty offshore pipelines when they are being laid. Upon the laying of such pipelines, considerable tensile stresses occur which are transferred by the holding devices of the laying ships to the steel pipes via the covering. The strip-shaped thickenings of the foil tape which are embedded in the concrete coating serve to increase the adherence between the plastic covering and the concrete jacket.